added norm examples to linalg.rst docs
better comments to example, use np.array instead of matrix
converted linalg.rst to use mat except for schur factorization, explained numpy.linalg vs scipi.alg, examplained numpy.ndarray vs numpy.matrix
fixed typos, improved comments, removed redundant np.arrray constructors, added scipy may be faster comment
Merge pull request #365 from cirosantilli/master

DOC: added norm examples to linalg.rst docs